The general goal of this research program is to analyze the relationship between different attentional limitations and attentional mechanisms. We will use fine-grained chronometric analyses and converging experimental designs to address four theoretical issues. The first is the relationship between the "central bottleneck" that often arises in dual-task performance and the idea of a "central executive" believed responsible for the control and coordination of task sets. A tight linkage between these concepts is sometimes assumed but with little empirical basis. We hypothesize that they may be dissociable, and will test this by asking whether controlled shifts in task set can occur in parallel with central processing in concurrent tasks. The second issue to be explored concerns the possibility of parallel memory retrievals. The literature offers seemingly contradictory suggestions regarding whether multiple memory retrievals can operate at the same time. We will test a number of hypotheses that might reconcile these apparent conflicts. Third, we will explore the relationship between affectively charged stimuli and central attentional limitations, asking, e.g., whether such inputs elicit expressive and autonomic reactions independent of the central bottleneck and looking at the effect of emotional stimuli on scheduling of central processes. Finally, we will explore a hypothesis termed consonance-driven orienting that describes a general principle that might govern the interaction of central cognitive processes and perceptual attention. Recent work from our laboratory provides tentative support for this hypothesis; new experiments, both visual and auditory, are proposed to further test and refine it.